1. Field of the Invention
The present invention relates to a magnetic type floor hinge that reduces the speed of opening and shutting of a door while absorbing undesirable mechanical impact, and more particularly, to a magnetic type floor hinge which is constructed in a non-contacted type by employing a magnetic damper.
2. Description of the Prior Art
A floor hinge is an auxiliary apparatus for a door, which is installed at the bottom surface of all sorts of doors (gates) and provides damping force so as to enable the doors to open and shut at a low speed.
In general, as shown in FIG. 1, a conventional floor hinge widely used is a hydraulic floor hinge and mainly comprises a main body 1, a piston 2, a compressing spring 3, a moving plate 4, a rod 5, a pin 6 and a cam 7. A pair of the pins 6 and the rod 5 are coupled to each other between the two moving plates 4. One end of the rod 5 is fixed to the piston 2 so that the moving plate 4, the pin 6, the rod 5 and the piston 2 move integrally. One end of the compressing spring 3 is fixed to the piston 2 and the other end is fixed to the interior of the main body 1. The interior of the main body 1 is divided into a hinge operating part 8 and a hydraulic operating part 9. The hydraulic operating part 9 is filled with oil and has an airtight structure. A pair of orifices 10 and 11 is formed at one end of the hydraulic operating part 9, which are opened or shut conversely with each other according to rectilinear movement of the piston 2.
In the conventional hydraulic floor hinge constructed as described above, when the door is opened, the cam 7 fixed to the rotating shaft of the door rotates and the pin 6 contacted with the cam 7 moves linearly. According to the linear movement of the pin 6, the piston 2 fixed to the rod 5 linearly moves and gets compressed. At the same time, the pair of orifices 10 and 11 are opened and clogged, respectively, by the piston 2 so that the oil flows from the high pressure portion of the compressed hydraulic operating part 9 to the low pressure portion where negative pressure is generated through the orifices 10 and 11 to generate damping force. The damping force generated as described above reduces the speed of movement of the piston 2 which goes straight on so that the damping force makes the door open or shut slowly at a low speed when the door is opened or shut. When the door is opened, the compressing spring 3 is compressed due to the forward movement of the piston 2, and then the piston 2 is regressed by the restitution force of the compressing spring 3. So although no force is applied to the door, the door becomes shut.
However, in the conventional hydraulic floor hinge constructed as described above, when the cam 7 pushes the pin 6, a torque is generated at the pin 6 around the rotating shaft of the cam 7 so that the piston 2 is contacted with the inner surface of the main body 1. Because of this, an abrasion is generated between the piston 2 and an inner wall of the main body 1. When oil leakage occurs between the piston 2 and the inner wall of the main body 1 due to the abrasion, the damping force of the hydraulic operating part is lowered. Thus, shutting speed of the door becomes faster than originally configured and the door is opened more easily.
Also, regarding the force for shutting the door, frictional force between the piston 2 and the inner wall of the main body 1 as well as frictional force between the cam 7 and the pin 6 should be considered in designing the conventional compressing spring 3 so that a spring constant of the compressing spring 3 is increased and an expected life span of the compressing spring 3 is reduced due to increase in the spring constant thereof.
Further, in the conventional hydraulic floor hinge, since the coefficient of viscosity of oil violently varies according to the temperature, there is a problem that the opening and shutting speed of doors is varied according to the change of temperature. Meanwhile, although a floor hinge which is provided with a control switch for controlling the opening and shutting speed of the door is disclosed, there are problems such as a rise in cost due to the addition of a device and inconvenience in use which a user has to control the control switch every time.
Therefore, an object of the present invention is to solve the above problems of the conventional floor hinge.
Another object of the present invention is to provide a magnetic type floor hinge which minimizes the friction force by applying the magnetic damper to the magnetic floor hinge and generating damping force in a way of non-contacted type and which can reduce the opening and shutting speed of the door constantly regardless of variation of temperature.
To achieve objects as described above, the present invention discloses a magnetic type floor hinge installed on the bottom surface of a door for maintaining the opening and shutting of the door at a low speed. The magnetic type floor hinge according to the present invention comprises an installing bracket divided into a magnetic operating part and a hinge operating part having one end on which a guide rail 33 is installed; a moving plate installed to move linearly on the guide rail 33; a compressing spring installed between the moving plate and the installing bracket in the moving direction of the moving plate; a main shaft cam rotatably installed on the upper portion of the moving plate, the main shaft cam being combined with a hinge shaft of the door and rotated along with the hinge shaft; a roller installed on one end of the moving plate, the roller being contacted with a cam-shaped surface of the main shaft cam; a disk rotatably installed at one end of the magnetic operating part of the installing bracket; a yoke installed on the magnetic operating part of the installing bracket, the yoke having permanent magnets attached thereto so as to generate repulsive force toward the upper and lower surfaces of the disk; and a gear-box in which a plurality of gears are received installed between the rotating shaft of the main shaft cam and the rotating shaft of the disk so as to convert the rotating movement of the main shaft cam at low speed to the rotating movement of the disk at high speed.